1. Field Of The Invention
This invention relates to a graphite-containing cathode coating dispersion for batteries with improved storage and discharge properties, which is applied to the cathode holder and forms an electrically conductive protective film.
2. Background Art
From Japanese Published Patent Document No.58-48361 (Japanese Patent) Application No. 56-145503 alkali dry cells are known which exhibit improved self-discharge properties. The improvement is attained by an electrically conductive protective film made of polyvinyl isobutyl ether and a carbon-containing material, applied to the inside of the cathode container. The materials are applied with the help of an organic solvent, e.g., xylene, and after evaporation of the solvent the electrically conductive film with rubberlike elasticity remains.
Japanese Published Patent Document No. 59-224054 (C.A. 102:175, 011f) also describes an electrically conductive composition of graphite and polyvinylpyrrolidinone on the inner surface of a battery container. Ethanol is proposed as the solvent for the polyvinylpyrrolidinone and as the carrier for dispersing the graphite.
The drawback of these coatings is the necessity of applying an organic solvent as the carrier of the components. But in the manufacturing process, in battery production, solvent vapors are undesirable and can lead to considerable breakdowns by exhaust air filter damage or require a special explosion protection.
The use of known type conductive varnishes do not attain the object either, since the corresponding films are not water-resistant.
The use of latices has further drawbacks, since they are not resistant in the prevailing oxidative conditions and in alkali medium.